Answer the following questions related to mass and weight.
(a) Define mass and weight, and state their SI units.
(b) An astronaut has a mass of 80kg on Earth. Explain whether his mass and weight will change when he lands on the Moon. Give reasons for your answer.
(c) A suitcase shows a reading of 196N on a spring balance at the equator. Will the reading be greater, equal, or less at the poles? Explain your answer with reference to the value of the acceleration due to gravity at these two locations.